1. Field of the Invention
The present invention relates to a storage system and a method of controlling power supply of the same, storage apparatus and data processing method. In particular, the invention is suitably applied to a storage system capable of recovering data at an arbitrary point in time by using update history of data.
2. Background Art
In recent years, data protection technology enabling the recovery of data at an arbitrary point in time by using update history of data referred to as a journal is attracting attention.
With this data protection technology, it is necessary to store all journals in order to enable the recovery of data at an arbitrary point in time and, as a result, the storage quantity of journals will continually increase.
Once a journal is stored in the storage device, such journal is rarely accessed until it is used in recovering data. Nevertheless, the actual situation is that a storage device storing journals is constantly in an operating state so that it can store an acquired journal at all times.
Pursuant to the increase of data to be protected in the future, it is anticipated that the accumulation of journals will also increase. Thus, it is envisioned that a means for reducing costs in retaining journals, which are hardly accessed, will become even more necessary.
Under the foregoing circumstances, Japanese Patent Laid-Open Publication No. 2000-293314 (Patent Document 1) discloses technology for suppressing the power consumption of the overall disk array device by turning off the power of a magnetic disk device, or switching to the power saving mode of such magnetic disk device, belonging to RAID (Redundant Array of Inexpensive Disks) that has not been accessed for a certain period of time (“power saving waiting time”).